Gaucher disease results from inherited mutations in the gene for the lysosomal enzyme, glucocerebrosidase (GC). Patients suffer from hepatosplenomegaly proceeding to hepatic failure, bone deterioration with multiple fractures and in some patients, progressive neurological degeneration. The symptoms in Gaucher disease are a consequence of the accumulation of the lipid substrate for glucocerebrosidase in lysosomes of tissue macrophages. Allogeneic bone marrow transplantation results in the replacement of enzyme deficient by normal ones but is associated with graft versus host disease. The approach adopted in this study has been to identify and separate the CDNA for human glucocerebrosidase. This is transferred via retroviral vector to CD 34 hemopoietic stem cells from patients with Gaucher's Disease and infused back to the patient. The objective is to determine the safety, efficacy and duration of gene expression.